Enhanced thermoelectric properties of polycrystalline CuCrS2-xSex (x = 0, 0.5, 1.0, 1.5, 2) samples by replacing chalcogens and sintering

The optimization of thermoelectric properties of the CuCrS2-xSex (x = 0, 0.5, 1.0, 1.5, 2) samples was achieved by substitution in anionic sublattice and sintering at high temperature. The maximum power factor PF ~ 0.3 mW/m•K^2 among a series of samples with chalcogen substitution was obtained for CuCrS0.5Se1.5 sample at T=300 K. The sintering made it possible to obtain the maximum value PF ~ 2.1 mW/m•K2 for CuCrSe2 sample. This is due to a more than threefold increase in the thermoelectric power S(T) in CuCrSe2 sample with a spin-orbital interaction in comparison with CuCrS0.5Se1.5 sample with the same optimal electrical conductivity σ (σ300K ~ 100 S/cm), but without spin-orbital interaction. In CuCrSe2 sample, sintering effectively reduced the s to an optimal value, suppressed of the magnetic phase transition in the range of 50-100 K, and the weak localization were replaced by weak antilocalization indicating the appearance of strong spin-orbit interaction below 20 K. As a result, an additional contribution to the S(T) appeared due to the filtration of current carriers caused by the strong spin-orbit interaction. The effect of grain boundaries on the properties σ(T) and S(T) of the samples was investigated. It was established that polycrystalline samples with a high sulfur content were low-conductivity materials consisting of high-conductivity crystallites with the charge carriers concentration n ~ 1020 cm-3 separated by low-conductivity grain boundaries with fluctuation-induced tunneling conductivity. Both the replacement of sulfur with selenium and sintering led to a decrease in the energy barriers connecting grain boundaries. Selenium-dominated samples (CuCrS0.5Se1.5 and CuCrSe2) had high electrical conductivity with negligible energy barriers between grain boundaries. Logarithmic quantum corrections to the electrical conductivity was observed below 20 K, which indicated a quasi-two-dimensional electron transport in these samples.

Electronic properties of orthorhombic InI and TlI crystals taking into account the quasiparticle corrections and spin-orbit interaction

The electronic properties of InI and TlI crystals of an orthorhombic structure with a space group Cmcm are studied. Calculations of electron properties are performed on the basis of the projector augmented waves by means of the ABINIT program. Total and partial densities of electronic states are calculated. Electron energy spectra are found with the exchange-correlation functional GGA, without and taking into account the spin-orbital interaction. It was found that the bandgap of the InI, obtained without spin-orbital interaction, is less than the experimental value by 38%, and by 42%, taking into account the latter. For the TlI crystal, the corresponding values are 27% and 39%. The bandgap found from the quasiparticle equation in the GW approximation exhibits an excellent agreement with the experimental values for both crystals.

Photonic Spin Hall Effect: Contribution of Polarization Mixing Caused by Anisotropy

Spin-orbital interaction of light attracts much attention in nanophotonics opening new horizons for modern optical systems and devices. The photonic spin Hall effect or Imbert-Fedorov shift takes a special place among the variety of spin-orbital interaction phenomena. It exhibits as a polarization-dependent transverse light shift usually observed in specular scattering of light at interfaces with anisotropic materials. Nevertheless, the effect of the polarization mixing caused by anisotropy on the Imbert-Fedorov shift is commonly underestimated. In this work, we demonstrate that polarization mixing contribution cannot be ignored for a broad range of optical systems. In particular, we show the dominant influence of the mixing term over the standard one for the polarized optical beam incident at a quarter-wave plate within the paraxial approximation. Moreover, our study reveals a novel contribution with extraordinary polarization dependence not observable within the simplified approach. We believe that these results advance the understanding of photonic spin Hall effect and open new opportunities for spin-dependent optical phenomena.

Hole States in Spherical Quantum Nanoheterosystem with Intermediate Spin-Orbital Interaction

The hole energy spectrum has been studied for the spherical semiconductor nanoheterosystem with the cubic symmetry. The exact solutions of the Schrödinger equation for the ground and excited hole states are presented within the framework of the 6-band Luttinger Hamiltonian and the finite gap of bands with the corresponding boundary conditions. Dependence of the holes energies from the radius of the quantum dot has been calculated for the GaAs/AlAs heterostructure. Obtained results where compared with data obtained using the infinite potential well model, as well as the single-band model for heavy and light holes.

Effect of spin-orbital interaction on continuous and jumpwise reversal magnetization in [Mn(II)(HL)(H2O)][Mn(III)(CN)6]·2H2O molecular ferrimagnet

Magnetic jumps were revealed during the magnetization reversal of [Mn(II)(HL)(H2O)][Mn(III)(CN)6]·2H2O molecular ferrimagnet. Amplitudes of the jumps were 0.01 – 0.1 % of the saturation magnetization. Fourier transform of the time series of jumps magnetization indicates that frequency spectrum is close to the white noise. Statistic distribution of the jumps versus time reveals the appearance of the most jumps at the beginning of the demagnetization. Effect of spin-orbit coupling on statistical distribution of magnetization jumps was considered by comparison of two compounds with different single ion anisotropies. The increase of spin-orbit interaction leads to the decrease of power of spectral density of magnetization jumps.